Hydroprocessing catalyst, preparation method thereof and use of same

ABSTRACT

The invention relates to a hydrocarbon hydroprocessing catalyst comprising a support based on at least one refractory oxide, at least one metal from group VIII and at least one metal from group VIB. The inventive catalyst is characterized in that it also comprises at least one organic compound having formula (I) or (II): 
                         
in which each R 1  represents independently an alkyl group at C 1-18 , an alkenyl group at C 2-18 , an aryl group at C 6-18 , a cycloalkyl group at C 3-8 , an alkylaryl or arylalkyl group at C 7-20 , or the two R 1  groups together form a divalent group at C 2-18 , and R 2  represents an alkylene group at C 1-18 , an arylene group at C 6-18 , a cycloalkylene group at C 3-7 , or a combination of same. The invention also relates to a method of preparing one such catalyst and to the use thereof for hydroprocessing or hydrocracking.

The present application is a Rule 53(b) continuation of application Ser.No. 11/795,411 filed Dec. 14, 2007, which is 371 national stage ofapplication No. PCT/FR2006/000126 filed Jan. 19, 2006, which claimpriority from French patent application No. 0500579 filed Jan. 20, 2005,the contents of all of which are incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

The present invention relates to a hydroprocessing catalyst, to themethod for the preparation thereof and to the use of this catalyst in amethod of hydroprocessing and/or hydrocracking hydrocarbons, inparticular hydrocarbons derived from petroleum fractions with a boilingpoint range of between 40 and 560° C.

Currently, the demand for desulfurized, denitrogenated and dearomatizedhydrocarbon compounds is increasing and manufacturers are developingcatalysts which are increasingly effective with respect to thepurification of hydrocarbons. However, these new catalysts are much moreexpensive and are accessible only from a limited number of producers. Inaddition, from their first regeneration, these catalysts exhibit anactivity that is often much lower than their initial activity in thefresh state under the same operating conditions. An additional specificrejuvenation treatment sometimes makes it possible to recover anactivity similar to the initial activity and thus makes it possible toreuse the catalyst for a further cycle of deep hydrodesulfurization andthe production of distillates having sulfur contents of less than 10ppm. Several rejuvenation treatments are proposed on the market.

They generally combine regeneration steps under specific conditions, andchemical and thermal treatments, and can be associated with ex situsulfurizations of the catalyst.

Numerous “conventional” catalysts, based on carriers formed ofrefractory oxide(s) and containing a combination of group VIB and VIIImetals are today used in refineries, in the fresh or regenerated state,either in hydroprocessing or in hydrocracking. If it proves to beimpossible to significantly increase their activity in desulfurizationand/or denitrogenation, these catalysts will have to be recovered,stored or destroyed when the specifications imposed with regard to fuelsbecome so restrictive that it will no longer be possible to use them.This storage or elimination of solids could also be subject toenvironmental and safety restrictions and could generate significantadditional costs for refiners.

DETAILED DESCRIPTION OF THE INVENTION

The Applicant has therefore sought, firstly, to render known catalystsbased on refractory oxide(s) and on group VIB and VIII metals moreeffective, and to confer on them desulfurization and denitrogenationactivities that are at least equivalent to those of the best catalystson the market, and, secondly, to improve the activity of regeneratedhydroprocessing catalysts in order to increase the number of recyclingcycles and to delay the point at which they are discarded and destroyed.

All hydroprocessing or hydrocracking catalysts containing metals in theoxide state, in order to be active, must necessarily be sulfurizedbefore use. This sulfurization can be carried out either in situ in thehydroprocessing reactor of the refinery, or ex situ.

The sulfurization can be carried out by means of hydrogen sulfide,mercaptans, organic sulfides, polysulfides and/or elemental sulfur,these compounds being introduced alone, as a mixture with a solvent, orat the same time as the feedstock.

Before this sulfurization step, some of these catalysts are premodifiedby a treatment with organic compounds.

The sulfurization and the premodification can be carried out in situ,i.e. in the hydroprocessing/hydroconversion reactor, or else ex situ,i.e. in a dedicated reactor. A premodification ex situ combined with asulfurization in situ in the hydroprocessing/hydroconversion reactor canalso be envisioned.

The range of organic compounds that can be used is quite broad. It isthus known practice to modify these catalysts by means of acids ofthioglycolic type, or else thioalcohols, thioacetone compounds andthiodiazoles, or thiocyanates as proposed, in particular, by thefollowing applications: EP 289211, EP 300629, EP 338788, EP 357295, EP456592, EP 478365 and EP 506206. Other catalysts have been modified bytreatment with alcohol-acid organic compounds (EP 482817), optionallyetherified mono-, di- or polyalcohols (EP 601722, U.S. Pat. No.3,954,673, U.S. Pat. No. 4,012,340, WO 01/76741), compounds of ureatype, polyamines, EDTA, hydrazine and other nitrogenous compounds (EP181035, EP 335754, EP 1043069, WO 01/76741, U.S. Pat. No. 3,954,673 andU.S. Pat. No. 4,012,340). Catalysts modified with C₂-C₁₄ monoesters aredescribed in patent applications EP 466 568 and EP 1046424.

All these compounds are aimed at improving the effectiveness of thecatalysts in hydroprocessing, more particularly in hydrodesulfurization.However, these modifications do not always make it possible tosufficiently increase the performance levels of the catalyst in order toface up to the specifications regarding sulfur contents in fuels whichare continually becoming more and more restrictive for refiners. Thus,for example, according to the guidelines of the European Parliament andof the European Council, European Community countries must producediesel fuel containing less than 50 ppm of sulfur from 2005 and lessthan 10 ppm by 2008-2011, while the 2004 standard is 350 ppm. Similarly,for all the countries of North America, the sulfur content of dieselmust go from 500 ppm to 15 ppm from 2006. Certain countries such asGermany are ahead of the European legislation and already make itobligatory to sell diesel at less than 10 ppm. Similar restrictionsalready apply to petrol and the other fuels. This change inspecifications imposes restrictions on the production by refineries, andrefiners must bow to these restrictions at the cost of oftenconsiderable investments in hydroprocessing or hydrocracking unitsand/or, much more economically, through improving the desulfurizationperformance levels of the current catalysts and the possibility ofrecycling them several times at their highest performance level.

With this aim, the Applicant has designed a new type of hydroprocessingcatalyst, based on refractory oxides and on metals of groups VIB andVIII of the Periodic Table of Elements, which exhibit, aftersulfurization, a greatly improved activity in desulfurization and indenitrogenation.

The subject of the present invention is thus a hydroprocessing catalystcomprising a carrier based on at least one refractory oxide, at leastone metal of group VIII and at least one metal of group VIB of thePeriodic Table of Elements, characterized in that it also comprises atleast one organic compound comprising at least two carboxylic esterfunctions, of formula (I) or (II)

in which

each R₁ independently represents a C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₆-C₁₈aryl, C₃-C₈ cycloalkyl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl group, orthe two R₁ groups together form a C₂-C₁₈ divalent group, and R₂represents a C₁-C₁₈ alkylene, C₆-C₁₈ arylene or C₃-C₇ cycloalkylenegroup, or a combination thereof,

it being possible for the carbon chain of the hydrocarbon-based groupsrepresented by R₁ and R₂ to contain or bear one or more heteroatomsselected from N, S and O, and for each of the groups R₁ and R₂ to bearone or more substituents of formula —C(═O)O—R₁ or —O—C(═O)—R₁ where R₁has the meaning indicated above.

In fact, the Applicant has established that the presence on thecatalysts of at least one organic compound of formula (I) or (II)increases the effectiveness of the catalysts in desulfurization and indenitrogenation, after activation by sulfurization under knownconditions. By using these new catalysts for hydrocarbonhydroprocessing, it is possible, in comparison with equivalent catalyststhat have not undergone any premodification, to reduce thedesulfurization reaction temperature by approximately 5 to 20° C., for agiven residual sulfur content and all operating conditions beingotherwise identical (pressure, amount of hydrogen and volume velocityper hour (VVH)). Such a gain in activity makes it possible to envisionobtaining residual sulfur contents that are much less than 50 ppm, oreven less than 10 ppm, in processed hydrocarbons, by varying theoperating conditions. If the unit is already able to produce alow-sulfur petroleum fraction, this gain in activity will make itpossible to reduce the temperature of the reactor for producing thedesired sulfur content, and thus to keep the unit operational for anadditional period that may be as long as several months.

The formulae (I) and (II) of the organic compound used in the presentinvention encompass compounds comprising two, three or four esterfunctions, or even more. In a preferred embodiment of the catalystaccording to the invention, the residues R₁ and R₂ do not generallycomprise any other ester substituents and the organic compound offormula (I) or (II) is a diester.

The number of carbon atoms separating the two groups >C═O of formulae(I) and (II) is preferably equal to 1, 2, or 4, and in particular equalto 1 or 2.

By way of examples of compounds of formula (I), mention may be made ofalkyl ortho-phthalates, alkyl isophthalates, alkyl terephthalates,malonic acid esters, adipic acid esters, glutaric acid esters,1,6-dioxacyclodecane-2,5-dione, dimethyl 2-(methoxymethyl)-succinate,dibutyl itaconate, diethyl 2,3-diacetylsuccinate, dimethylcyclohexane-1,4-dicarboxylate and dimethyl 3,3′-dithiodipropionate.

By way of examples of compounds of formula (II), mention may be made ofglycerol triacetate, propylene glycol diacetate, ethylene glycoldimethacrylate and pentaerythritol tetrakis(3-mercaptopropionate).

In a preferred embodiment of the present invention, the compound offormula (I) is a C₁-C₄ dialkyl succinate, preferably dimethyl succinate.

Preferably, the nonmodified catalyst, known per se, is a catalystconsisting of a refractory oxide carrier of alumina, silica orsilica-alumina type containing from 0.1% to 10% by weight of at leastone metal of group VIII, preferably nickel and/or cobalt, and from 1% to20% by weight of at least one metal of group VIB, preferably molybdenum.

The catalyst may be a fresh, i.e. nonregenerated, catalyst originatingdirectly from a manufacturer, but the pretreatment according to theinvention with one or more compounds of formula (I) or (II) is alsoadvantageous when it involves a catalyst generally regenerated by meansof an appropriate chemical or thermal treatment, for example by means ofcalcination.

It is nevertheless known that, due to a specific method of preparation,certain fresh catalysts can be more or less refractory to therecommended treatments. Similarly, for the same reasons or subsequent tospecific operating conditions experienced in the unit, regeneratedcatalysts can prove to be more or less refractory to these treatments.

The catalyst according to the invention preferably contains at least0.001 mol of organic compound(s) of formula (I) or (II), in particularfrom 0.001 mol to 10 mol, preferably from 0.01 to 6 mol, and even morepreferably from 0.1 to 3 mol of compound(s) of formula (I) or (II) permole of metals of groups VIB and VIII.

A subject of the invention is also a method for preparing the modifiedhydroprocessing catalyst described above. This method of modificationcomprises bringing a catalyst comprising a carrier based on at least onerefractory oxide, at least one metal of group VIII in the oxide stateand at least one metal of group VIB in the oxide state into contact withat least one organic compound of formula (I) or (II)

in which

each R₁ independently represents a C₁-C₁₈ alkyl, C₂-C₁₈ alkenyl, C₆-C₁₈aryl, C₃-C₈ cycloalkyl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl group, orthe two R₁ groups together form a C₂-C₁₈ divalent group, and R₂represents a C₁-C₁₈ alkylene, C₆-C₁₈ arylene or C₃-C₇ cycloalkylenegroup, or a combination thereof, it being possible for the carbon chainof the hydrocarbon-based groups represented by R₁ and R₂ to contain orbear one or more heteroatoms selected from N, S and O, and for each ofthe groups R₁ and R₂ to bear one or more substituents of formula—C(═O)O—R₁ or —O—C(═O)—R₁ where R₁ has the meaning indicated above.

According to the invention, the bringing into contact is generally andpreferably an impregnation.

When the compound(s) of formula (I) or (II) is (are) liquid(s) at theimpregnation temperature, the bringing into contact can be carried outin the absence of solvent. The bringing of the nonmodified catalyst intocontact with the organic compound(s) of formula (I) or (II) ispreferably carried out by bringing the catalyst into contact with asolution containing the organic agent(s). The volume of solution may beless than, equal to or greater than the pore volume of the catalyst. Themethod using a volume of solution less than or equal to the pore volumeof the catalyst is sometimes called “dry impregnation”. When the volumeof solution is greater than the pore volume of the catalyst, the excesssolution will be eliminated after the adsorption of the organiccompound(s) of formula (I) or (II) onto the catalyst.

The catalyst can be brought into contact with the compound(s) of formula(I) or (II) in the presence of at least one solvent.

When the bringing into contact is carried out in the presence ofsolvent, the organic compound(s) of formula (I) or (II) is (are)preferably at least partially soluble in the solvent used. The choice ofthe solvent is of particular importance in the implementation of themethod. The selection of the solvent is based on various criteria, suchas its solvent capacity for the compound(s) of formula (I) or (II), itsdispersing effect on the compound(s) of formula (I) or (II), its wettingeffect on the surface of the catalyst and its availability on the marketunder economically acceptable conditions.

Among the solvents that will advantageously be used in the invention,mention may be made of water, supercritical fluids such as carbondioxide, aromatic, aliphatic or alicyclic solvents, petroleum fractions,mono- and polyhydroxylated solvents such as ethanol, tert-butanol,ethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, polyethylene glycol (PEG), glycerol, alkyl esters such as ethylacetate, ketones such as acetone or methyl ethyl ketone,N-methylpyrrolidone, solvents containing an amide function such asdimethylacetamide, solvents containing a nitrile function such asacetonitrile, alkyl carbonates such as ethyl carbonate, ethers such astetrahydrofuran, sulfur-containing solvents such as dimethyl sulfoxideand sulfolane, acids such as acetic acid, and halogenated solvents, or amixture of several of these solvents.

Among these solvents, preference is in particular given to water,toluene, xylenes, ethylene glycol, diethylene glycol, triethyleneglycol, glycerol, ethanol, tert-butanol, polyethylene glycol (PEG), mostcommonly of molecular weight from 118 (triethylene glycol) to 1000,white spirit and petroleum ether.

The organic compound(s) of formula (I) or (II) can optionally beintroduced in the presence of at least one acid, generally selected fromcarboxylic acids, hydrocarboxylic acids and polyacids (such as formicacid, acetic acid, glycolic acid, lactic acid, tartaric acid, maleicacid, citric acid, glyceric acid, gluconic acid, methoxyacetic acid,ethoxyacetic acid, malonic acid, L-(+)-ascorbic acid, salicylic acid,oxalic acid, orthophthalic acid, succinic acid, glyoxylic acid, etc.),thiocarboxylic acids (such as thiobenzoic acid, mercaptoacetic acid, 1-and 2-mercaptopropionic acid, 2,3-dimercaptosuccinic acid,mercaptosuccinic acid, thioacetic acid, thioglycolic acid,thiodiglycolic acid, dithiodiglycolic acid, etc.), aminocarboxylic acids(nitrilotriacetic acid, EDTA (ethylene-diaminetetraacetic acid). Amongthese acids, the acids particularly preferred are lactic acid, maleicacid, tartaric acid, citric acid, succinic acid, oxalic acid, thioaceticacid, thioglycolic acid, nitriloacetic acid and EDTA.

The acid(s) can be introduced with the compound(s) of formula (I) or(II) or separately, if, for example, the mixture obtained is nothomogeneous. In this case, it may be advantageous to use a solvent whichallows the simultaneous introduction of the acid(s) with the compound(s)of formula (I) or (II), the solvent then ensuring dissolution of all theorganic compounds present. Finally, it is also possible, when theacid(s) is (are) introduced separately (before or after, preferablybefore) from the compound of formula (I) or (II), to use a solventdifferent than that used to introduce the compound of formula (I) or(II).

The bringing into contact of the catalyst, optionally predried atbetween 10 and 600° C., preferably between 15 and 300° C., morepreferably from 20 to 180° C., with a solution of one or more compoundsof formula (I) or (II) during the impregnation step can last from 1minute to 7 days, preferably from 10 minutes to 8 hours, at atemperature of between 0° C. and 200° C., preferably at ambienttemperature, at a low pressure of between atmospheric pressure and 5bar, preferably at atmospheric pressure. When a solution of acid(s) isintroduced before the solution of organic compound(s) of formula (I) or(II), the operating conditions for the impregnation with the acid(s) aresimilar to those for the impregnation with the organic compound(s) offormula (I) or (II). In the optional case where the catalyst is dried,it is possible to advantageously take advantage of the residual heat ofthe catalyst to carry out a hot impregnation.

At the end of the impregnation step, the catalyst can be subjected,optionally after elimination of an excess of impregnation solution, toan optional maturation step at a temperature generally of from 0 to 100°C., preferably ambient temperature (approximately 20° C.) to 80° C.,generally at atmospheric pressure or up to pressures that are generallyused in hydroprocessing or hydroconversion methods, the duration ofwhich may be between a few minutes and a few years, when the catalystwould remain stored in vats. Preferably, the maturation step can lastfrom a few minutes to 2 days. An optional thermal treatment, consecutiveto the maturation step, can be carried out at temperatures of from 50°C. to 250° C., preferably from 60 to 180° C., lasting from a few minutesto several days, preferably from 30 minutes to 3 hours, under an inertor noninert atmosphere, with or without gas flow, generally atatmospheric pressure or up to pressures that are generally used inhydroprocessing or hydroconversion methods.

The optional maturation and thermal treatment steps can possibly beomitted when the catalyst is loaded directly into the hydroprocessing orhydroconversion unit.

The catalyst modified by impregnation with the compound(s) of formula(I) or (II) is completely stable at ambient temperature and when exposedto the air. The modification of the catalyst can consequently be carriedout ex situ, i.e. outside a hydroprocessing, generally hydroconversion,reactor, and this is a preferred embodiment of the method according tothe invention. The ex situ implementation of the method according to theinvention can optionally be combined with an ex situ sulfurization ofthe modified catalyst according to the invention. This allows therefiner to purchase a product immediately ready for use and to reduce asmuch as possible the time lost when initiating the unit.

It is also advantageous to carry out the step of modification of thecatalyst with the compound(s) of formula (I) or (II) ex situ, and tosulfurize the modified catalyst in situ in the hydroprocessing reactor.In this case, the catalyst can be placed in the processing unit moreeasily since, unlike the sulfurized catalyst, there is no risk of thenonsulfurized catalyst self-igniting.

Yet another variant consists in carrying out both the modification ofthe catalyst and the subsequent sulfurization in situ. In this case, themethod of preparation according to the invention is characterized inthat the catalyst is brought into contact with the compound(s) offormula (I) or (II) in the presence of hydrogen and of at least onesulfurization agent preferably selected from hydrogen sulfide, elementalsulfur, CS₂, mercaptans, sulfides and/or polysulfides, and hydrocarbonfractions with a boiling point of less than 400° C. containing sulfurcompounds, generally in a hydroprocessing reactor.

It should be noted that, even when the modification of the catalyst withthe compound(s) of formula (I) or (II) is carried out in situ in thehydroprocessing reactor, these two operations generally constitute twoseparate steps carried out one after the other, the bringing intocontact with the compound(s) of formula (I) or (II) always preceding thesulfurization step. However, these two steps can also be carried outsimultaneously.

In addition to the impregnation of the organic compounds into the poresof a fresh or regenerated catalyst, it is also possible to introducesaid organic compounds during the manufacturing/forming of the catalyst.It is, for example, possible to incorporate the organic compound(s) offormula (I) or (II) into the carrier, even before the deposition of thecompounds of metals of groups VIB and VIII. This can be done by mixingone or more organic compounds with the constituents of the carrierbefore the forming of the latter, or else by impregnating the carrierformed with the organic compounds.

Another possibility consists in introducing the organic compound(s) andthe compounds of metals of groups VIB and VIII simultaneously, either bymixing them with the constituents of the carrier before forming, or byimpregnating an already formed carrier with both the organic compound(s)and the salts of metals of groups VIB and VIII. One or other of theoperations can be followed by drying, carried out under conditions suchthat at least a part of the organic compounds is conserved in thecatalyst.

It is also possible to incorporate the organic compounds of formula (I)or (II) only after the salts of metals of groups VIB and VIII. One orother of these steps can optionally be followed by drying and/orcalcination under conditions such that at least a part of the compoundsis conserved in the catalyst.

The organic compound(s) of formula (I) or (II) can be introduced intothe catalyst in liquid and/or particulate solid form and/or in the formof a solution or suspension in an appropriate solvent.

A subject of the invention is also a method of in situ or ex situactivation of a hydroprocessing catalyst as described above. Thisactivation is carried out by placing the catalyst in the presence,simultaneously or successively, of hydrogen and at least onesulfurization agent preferably selected from hydrogen sulfide, elementalsulfur, CS₂, mercaptans, sulfides and/or polysulfides, and hydrocarbonfractions with a boiling point of less than 400° C. containing sulfurcompounds. A preferred sulfurization agent is dimethyl disulfide (DMDS).

The sulfurization agent can be introduced in the form of a gas or in aform diluted in a solvent, or as an additive for the feedstock to behydroprocessed.

Finally, a subject of the invention is the use of the catalyst thusactivated in situ or ex situ, for the hydroprocessing and/orhydrocracking of hydrocarbons, in particular of hydrocarbons derivedfrom petroleum fractions with a boiling point of between 40 and 560° C.

The examples given in the remainder of the present description are aimedat illustrating and not at limiting the invention.

Example 1

In the present example, a method of preparing the catalysts according tothe invention is described, these catalysts then being used in exampleIII.

The starting material is a commercial catalyst (catalyst A), consistingof a combination containing 3% by weight of cobalt and 10% by weight ofmolybdenum on an alumina carrier, available on the market and commonlyused by refiners in hydrodesulfurization units.

The modification of this catalyst A with a compound of formula (I) iscarried out in the following way: 200 g of catalyst A are placed in theround-bottomed flask of a rotary evaporator rotating at 45 rpm. Asolution consisting of 53.3 g of dimethyl succinate dissolved in 66 mlof toluene is injected, over 35 minutes, into the heart of the catalyst.The impregnated solid is left to slowly rotate (20 rpm) for 16 hoursbefore being subjected to a reduced pressure, equal to 2700 Pa, and atemperature of 50° C. for 30 minutes. After most of the toluene has beenevaporated off, a catalyst with a dry appearance is obtained.

After 115 days at ambient temperature, 100 ml of this catalyst areloaded into a reactor of a pilot unit for desulfurization of diesel oilfor the purpose of carrying out an activity test as described in exampleIII. After loading, the catalyst is subjected to heat treatment at 180°C. for 2 hours, and then to further heat treatment at 150° C. for 14hours, the whole under a stream of nitrogen of 20 l/h. The catalyst thusobtained is called catalyst B.

Example II

In the present example, a method of preparing the catalyst according tothe invention in the absence of solvent is described. This catalyst isthen used in example III.

100 g of catalyst A are placed in the round-bottomed flask of a rotaryevaporator and then rotated at 45 rpm. 54.8 g of dimethyl succinate areinjected, over 12 minutes, into the heart of the catalyst. Theimpregnated solid is then heated at 50° C. for 30 minutes in order toaccelerate the dispersion of the liquid in the catalyst.

After storage for 49 days at ambient temperature, 100 ml of thiscatalyst are loaded into the reactor of the diesel oil desulfurizationpilot unit for the purpose of carrying out the activity test describedin example III. The catalyst is subjected to heat treatment at 150° C.for 16 hours under a stream of nitrogen of 20 l/h. This catalystaccording to the invention is called catalyst C.

Example III

Each of catalysts B and C (according to the invention) is sulfurizedwith a diesel oil with 2% by weight of added dimethyl disulfide (DMDS)according to the procedure recommended by the manufacturer of catalystA.

In the present example, the activity of catalysts B and C havingundergone a modification according to the invention (example I and II)is compared with that of catalyst A not having undergone anymodification treatment.

After sulfurization and stabilization of the three catalysts A, B and C,a feedstock comprising a mixture of 70% by weight of diesel oil and 30%by weight of a hydrocarbon fraction of LCO (light cycle oil) typederived from catalytic cracking is introduced. The characteristics ofthis feedstock, before hydroprocessing, are indicated in table I below.

TABLE I 30% LCO-70% Feedstock type diesel oil mixture Sulfur (ppm) 9074Density at 15° C. (g/ml) 0.8863 Monoaromatics (% by weight) 20.7Diaromatics (% by weight) 21.3 Triaromatics (% by weight) 3.8 Σaromatics (% by weight) 45.8 Nitrogen (ppm) 389 Distillation accordingto standard ASTM D86 (° C.) Initial point 180  5 vol % 224 50 vol % 29195 vol % 360 Final point 361

The hydroprocessing reaction is carried out under a pressure of 27×10⁵Pa (27 bar) with a hydrogen/hydrocarbon (H₂/HC) ratio of 250 Nl/l at avolume velocity per hour (VVH) of 1 h⁻¹.

To compare the desulfurization activities, the reaction temperature isadjusted, for each catalyst, to a value corresponding to a degree ofdesulfurization of 99%. The lower this temperature, for catalysts B andC according to the invention, in comparison with the correspondingtemperature for the reference catalyst A, the more active thesecatalysts are in desulfurization.

The results obtained are represented in table II in the form of atemperature difference (ΔT) relative to the reference temperature ofcatalyst A (T_(HDS)). They correspond to the temperature required toreach a degree of desulfurization of 99%.

TABLE II Catalyst A B C HDS T_(HDS) T_(HDS) − 7° C. T_(HDS) − 7° C.

It is noted that catalysts B and C according to the invention make itpossible to reach a degree of desulfurization of 99% at a temperature 7°C. lower than that required for catalyst A. They therefore have ahydrodesulfurization activity greater than that of catalyst A.

To compare the denitrogenation activities, the residual nitrogen contentfor a given reaction temperature T_(HDN) is measured for each catalyst.The lower this residual nitrogen content, the more active the catalystis in denitrogenation.

The results obtained are represented in table III.

TABLE III Catalyst A B C Residual nitrogen content 120 78 60 at T_(HDN)(ppm)

It is noted that catalysts B and C according to the invention make itpossible to reduce the residual nitrogen content to a greater extentthan catalyst A, thereby showing that they are also more active indenitrogenation.

The invention claimed is:
 1. An activated hydroprocessing catalystcomprising a carrier based on at least one refractory oxide, at leastone metal of group VIII and at least one metal of group VIB of thePeriodic Table of Elements, and at least one organic compoundrepresented by formula (I), the at least one organic compound having atleast two carboxylic ester functions and wherein the activated catalystis prepared by bringing the at least one organic compound in contactwith a regenerated catalyst which comprises the at least one refractoryoxide, at least one metal of group VIII and at least one metal of GroupVIB followed by activation by sulfurization,

in which each R₁ independently represents a C₁-C₁₈ alkyl, C₂-C₁₈alkenyl, C₆-C₁₈ aryl, C₃-C₈ cycloalkyl, C₇-C₂₀ alkylaryl or C₇-C₂₀aryalkyl group, or the two R₁ groups together form a C₂-C₁₈ divalentgroup, and R₂ in formula (I) represents a C₁-C₁₈ alkylene, C₇-C₁₈arylene or C₃-C₇ cycloalkylene group, or a combination thereof, it beingpossible for the carbon chain of the hydrocarbon-based groupsrepresented by R₁ and R₂ to contain or bear one or more heteroatomsselected from N, S and O, and for each of the groups R₁ and R₂ to bearone or more substituents of formula —C(═O)O—R₁ or —O—C(═O)—R₁ where R₁has the meaning indicated above, wherein the hydroprocessing catalysthas been subjected to a thermal treatment at a temperature between 60°C. and 180° C. following impregnation step during preparation of thehydroprocessing catalyst.
 2. The activated hydroprocessing catalyst asclaimed in claim 1, wherein the organic compound of formula (I) isselected from malonic acid esters, adipic acid esters, glutaric acidesters, 1,6-dioxacyclodecane-2,5-dione, dimethyl2-(methoxymethyl)succinate, dibutyl itaconate, diethyl2,3-diacetylsuccinate, dimethyl cyclohexane-1,4-dicarboxylate, anddimethyl 3,3′-dithiodipropionate.
 3. The activated hydroprocessingcatalyst as claimed in claim 1, wherein the number of carbon atomsseparating the two groups >C═O of formula (I) is equal to 1, 2 or
 4. 4.The activated hydroprocessing catalyst as claimed in claim 3, whereinthe organic compound of formula (I) is a C₁-C₄ dialkyl succinate.
 5. Theactivated hydroprocessing catalyst as claimed in claim 4, wherein theorganic compound of formula (I) is dimethyl succinate.
 6. The activatedhydroprocessing catalyst as claimed in claim 3, wherein the number ofcarbon atoms separating the two groups >C═O of formula (I) is equal to 1or
 2. 7. The activated hydroprocessing catalyst as claimed in claim 1,wherein the catalyst comprises at least 0.001 mol of at least oneorganic compound per mole of metals of groups VIB and VIII.
 8. Theactivated hydroprocessing catalyst as claimed in claim 7, wherein thecatalyst comprises from 0.001 to 10 mol of at least one organic compoundper mole of metals of groups VIB and VIII.
 9. A method for preparing anactivated hydroprocessing catalyst according to claim 1, comprising inthis order: a step of bringing a regenerated catalyst comprising acarrier based on at least one refractory oxide, at least one metal ofgroup VIII in the oxide state and at least one metal of group VIB in theoxide state into contact with at least one organic compound of formula(I)

in which each R₁ independently represents a C₁-C₁₈ alkyl, C₂-C₁₈alkenyl, C₆-C₁₈ aryl, C₃-C₈ cycloalkyl, C₇-C₂₀ alkylaryl or C₇-C₂₀arylalkyl group, or the two R₁ groups together form a C₂-C₁₈ divalentgroup, and R₂ in formula (I) represents a C₁-C₁₈ alkylene, C₇-C₁₈arylene or C₃-C₇ cycloalkylene group, or a combination thereof, it beingpossible for the carbon chain of the hydrocarbon-based groupsrepresented by R₁ and R₂ to contain or bear one or more heteroatomsselected from N, S and O, and for each of the groups R₁ and R₂ to bearone or more substituents of formula —C(═O)O—R₁ or —O—C(═O)—R₁ where R₁has the meaning indicated above, and a step of activating the catalystby sulfurization.
 10. The method as claimed in claim 9, wherein the stepof bringing the at least one organic compound in contact with thecatalyst is followed by at least one maturation step, at a temperaturefrom 0 to 100° C., the duration of which is between a few minutes and afew years, said maturation step being optionally followed by at leastone heat treatment step, at a temperature of from 60° C. and 180° C.,and lasting from a few minutes to several days.
 11. The method asclaimed in claim 9, wherein the catalyst is brought into contact withthe compound(s) of formula (I) in the presence of at least one solventand of at least one acid.
 12. The method as claimed in claim 9, whereinthe organic compound(s) of formula (I) are at least partially soluble inthe solvent.
 13. The method as claimed in claim 11, wherein the solventis selected from water, toluene, xylenes, ethylene glycol, diethyleneglycol, triethylene glycol, glycerol, ethanol, tert-butanol,polyethylene glycol (PEG) white spirit and petroleum ether.
 14. Themethod of preparation as claimed in claim 13, wherein the solvent has amolecular weight from 118 to
 1000. 15. The method of preparation asclaimed in claim 14, wherein the solvent is triethylene glycol.
 16. Themethod of claim 12, wherein the solvent is polyethylene glycol having amolecular weight from 118 to
 1000. 17. The method of claim 16, whereinthe solvent is triethylene glycol.
 18. The method as claimed in claim 9,wherein the catalyst is brought into contact with the compound(s) offormula (I) ex situ, outside the hydroprocessing reactor.
 19. The methodas claimed in claim 9, wherein the activation step comprises placing thecatalyst in the presence of hydrogen and of at least one sulfurizationagent preferably selected from hydrogen sulfide, elemental sulfur, CS₂,mercaptans, sulfides and polysulfides, and hydrocarbon fractions with aboiling point of less than 400° C. containing sulfur compounds.
 20. Themethod as claimed in claim 9, wherein the sulfurization agent isdimethyl disulfide.
 21. The method as claimed in claim 9, wherein thecatalyst is brought into contact with the compound(s) of formula (I) inthe presence of at least one solvent or of at least one acid.
 22. Amethod of using the activated hydroprocessing catalyst of claim 1, themethod comprising a step of bringing the activated catalyst in contactwith hydrocarbons derived from petroleum fractions with a boiling pointof between 40° C. and 560° C.